Diffusion tensor image illuminates "white matter," bundles of long fibers (axons) that transmit signals between different parts of the brain. Colors indicate the direction in which the bundles are running (green = back to front, red = side to side, blue = top to bottom). The gray "base"—an MRI slice through the brain showing the eyes—and the outline of the head are included to help orient the image in space. The bundles dangling beneath the base are going to the brain stem and temporal lobe. Such images could be used to help surgeons excise brain tumors without damaging fiber bundles.

Image courtesy of the Vanderbilt University Institute of Imaging Science; illustration by Dominic Doyle

Since the discovery of the X-ray, scientists have tried to take pictures of the mind at work.

One hundred ten years later, they have never been closer.

Soon it may be possible to predict—and avert—the development of drug addiction, to individualize therapy for schizophrenia and other disorders, and to preserve and even augment brain function.

“Traditionally, imaging meant radiology—you went to the X-ray department. Imaging is now much more broadly based,” says John C. Gore, Ph.D., director of the Vanderbilt University Institute of Imaging Science.

Now, techniques like functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) provide much more than a static snapshot of the brain’s form. They can illustrate the symphony of activity that underlies memory, addiction and love. They can also resolve dysfunction related to psychiatric and neurological disease and watch how drugs and educational interventions “normalize” brain activity.

“Can we measure the effect of a behavioral therapy? Can you tell whether someone is going to recover from aphasia? Those are questions that radiologists have not previously thought much about,” Gore says. “They now have the tools to do it.”